Threading spindle



`lune 6, 1939.

E. J. STAHLHAMMER THREADING SPINDLE Filed Aug. 25, 1957 2 Sheets-Sheet l June 6, 1939.

E. J. STAHLHAMMER THREADING SPINDLE Filed Aug. 25, 1957 2 Sheets-Sheet 2 nIlm u w 0 x 3` f/MA... JM

Eric' ,Sta/z Mammal Bly C? ATTORN Patented June 6, 1939 UNITED STATES PATENT oFFl-CE 2,161,265 THREADING STPINDLE Application August 25,

14 Claims.

This invention relates to' screw-threading machines, particularly to that class thereof which will" cut external threads on smalll workpieces which cannot be grasped or clamped in: chucks .fi-'i1 and1 hel-d therein during the threading operation. For instance, it has always been a diicult problem tocut true and'full length screw threads on the oute surface of cylindrical blanks, espe- I eiall'y of smallersizea'like those of the so-called To?? Allen headless set screws, because therev is no way in which these blanks can be externally chucked, the` threading tool traversing the entire' length'of the blanks outer surface. Consequently l theY only expedient heretofore resorted to, was 151* to place the blank onto an arbor whose shape and size correspond at least approximately to therecess (formed usually square, sometimes triangular)` extending into one end of the blank for the normali purpose of receiving the squared or triangular shank of a' wrench toolr to drive the finished" screw intol a tapped hole prepared forV be held in true axial position during the period when the Idie chasers ofthe machineY are doing the thread cutting, and alsoV when they areV reversely operated to leave the newly-threaded blank free to bey removed from its arbor.

In the present instance, the invention isY shown as being incorporated in a vertical type ofma'- n chine, that is to say rthat type in which the ,1l-1! threading spindles, which may consist of one or more, are movable vertically to do their work on blanks which latter are positionedon arbors located on a horizontal table turntable onl a I vertical axis to bring successive blanks into alignment with the spindles, respectively, the

table however having no vertical movement. Of course, it should bev understood that the invention, as such, is applicable to other types of` Ymachines; as well. Each blank isl placed on its oi lower forged wrench-recess seated on the arbor, while its upper conical and usually countersunk end is brought into vertical alignment with the spindle which isto do the thread cutiftinglf When in this position, the upper blank .Inl order to avoid this objection, the present' arbor (carried by the table), so as to have its 1937;` serial No'. 160,828'

end` will beengaged by' a plunger whose lower end is adapted to seat itself in the countersunk top'portionof the blank and thus hold the latter in xed position at the top while the arbor holds the lower recessed end, both ends being then in central vertical alignment.r

The plunger just referred to is vertically movable inthe spindle and'is, in the present instance, forced' downward by force of oil pressure introduced into'the upper end of the spindle, the latt'er constituting' a cylinder in which the plunger can moi/'e in amanner similar to that of a piston, but whieh'becomes stationary when its lower end engages ther upper countersunk end of the blank, withoi'it,` however', interfering with the vertical downwardmovement of the spindle which carries the chasers.

InA accordance with the present invention, a portion ofrthis pressure oil is permitted to pass to thev bottoni; end ofj the plunger, the latter having one o r more small longitudinal surface grooves which permit the passage of a small amount of oil'therethrough, so thatV this leakage oilbecomes usable as a lubricant or cutting oil for the threading chasers, a feature which is important infpracticeand is here entirely automaticl in action.

As above/stated, in the present machine the work-*supporting tablevdoes not move vertically; butthe threading spindles are carried by a slide whichV isl moved verticallyY during the threadcutting operation in the usual mannen and so that themdescendingmovement per revolution of thelspiii'dles isniore than the downward travel orl p itfch of the chasers. In other words, the spindle consists really of two telescopic lengths, theouter onembving with the machine slide, the innerone carrying ,theA cutting chasers and therefore" being limited* in. its vertical movement as dependentI uponthef chaser' pitch, which is less than the vertical longitudinal movement prescribed for the outer spindle section. To permit this greater movement of the outer spindle section, a' spring' is interposed between the two sections and willbe compressed'when the outer section' descends faster than the inner chaser section.

Other objects of theinve'ntion will hereinafter appear.

f Referring to theA drawings:

Figure' l' is a central vertical section of the completejthreading spindle assemblage as secured tothe" vertically movable slide of the machine, and'lshfows'also a portion of the revoluble worksuppor'ting table in position on the knee of the machine, together with the stop device for limiting the downward threading movement of the chasers to a predetermined depth.

Fig. 2 is a side elevation corresponding to Fig. 1.

Figs. 3, 4, 5 and 6 show different progressive positions of the chasers relative to the work, Fig. 3 being the initial condition of the parts. Fig. 4 shows the blank held in place on its arbor, and spindle lowered to almost bring the chasers into contact with the blank. Fig. 5 illustrates the chasers after they have completed their work of externally threading the full length of the blank and are ready to move upward again, upon reversal of the spindle rotation. Fig. 6 shows the spindle raised again to have the chasers clear of the now threaded blank, and the down-holding plunger still in action.

Fig. '1 is a side View of the oil-actuated downholding plunger, per se.

Fig. 8 is a top view thereof.

Fig. 9 is a horizontal section, on line 9 9, of Fig. 1.

inasmuch as the type of machine, to which the subject matter of the present invention has been exemplarily applied, is well known in the art, the drawings show fractionally only such parts thereof as may be required for a better understanding of the functions which the new parts are to perform. In Fig. 1, the numeral I denotes a portion of the machine knee, which is usually vertically adjustable only, to accommodate workpieces of different heights. This otherwise stationary knee carries a work-supporting table II rotatablein a circular recess I2 and on a vertical axis on the knee and provided with individual work supports I3 which are securely clamped thereto.

The upper part of the machine has the usual main .slide I4, which is vertically movable, either manually or automatically, to bring the tool spindles into or out of engagement with the work on the knee table Il. The tool spindles S (of which there may be several) are each supported for Vertical rotation in a barrel bearing I having the usual slotted tailpiece I6 to permit the spindle to be properly positioned on the slide I4 and clamped there by a bolt I1. The spindle consists of a pair of telescopically arranged parts, the outer tubular section I8 being journaled but not slidable in the barrel bearing I5, suitable roller bearings I9 being provided to insure a close running nt between these parts. At its lower end the tube I8 has a nut I9 which :not only permits a 'close adjustment of the lower roller bearing I9 but also prevents upward movement of the tube I 8 in the barrel I5. In a similar manner, downward movement of the spindle tube I8 is prevented by an annular ilange 20 to which the spindle-driving pinion 2I is secured by screws, as shown in Fig. l. Poweris transmitted to the pinion 2l by an intermediate gear 22 which is journaled on a stud 23 carried by a sweep 24, supported on the upper portion I5 of the barrel I5 and adapted to be swung around the same to bring the intermediate gear 22 into proper engagement with whatever central main gear the machine is equipped with, for obtaining various speeds as required, thesweep 24 being then xed on the barrel by a wedge pin 25, as usual.

Above the upper spindle flange 20, the spindle tube I8 is provided with a tubular extension 26 to receive a driving head 21 whereby the inner or tool spindle 28 is indirectly rotated by the pinion, the driving connection being as follows: The tubular extension 26 (see Fig. 9) is longitudinally slotted at diametrically opposite portions of its shell to form pairs of parallel contact faces 26a, 2Gb in which side wings 21a., 21h, projecting from the head 21 are positioned for connecting the tool spindle extension 25 with the head 21, so that, when the extension pinion 2| is driven, the head 21 and the tubular spindle portion I8 will also be rotated, by way of the head wings 21a, 21b, contacting the faces 26a, 25h, respectively. Broadly speaking, the spindle tube I8 is, in reality, only a driver for the actual tool-carrying spindle 28, the tool in the present instance being shown as a solid chaser die D secured to the lower face of a tool block 30 by screws 3I which permit substitution of various sizes of dies for the one in use. The block 30 has preferably a pipe-thread connection with the lower end 32 of the inner tool spindle 28 which consisted heretofore of a solid rod vertically movable in the spindle tube, but which in the present invention incorporates some new features to be described hereinafter.

Considering the tool spindle 28 in connection with its driving mechanism, its upper portion (above the sweep 24) has two opposite sides flatted, as at 28a, to t a correspondingly shaped slot provided for it in the head 21, these flatted sides constituting a sliding key-connection between the spindle 28 and head 21, the latter being longitudinally adjustable on the tube to control the limit of downward movement which the tool may attain relative to the outer tubular spindle I8, it being evident that, unless the machine slide I4 moves downward, the tool spindle cannot descend any farther. On the other hand, if the slide I4 does descend, the tool spindle 28 will go down with it until it is stopped by a depth gage G, shown herein as a vertically movable slide 35 comprising a fork 35a which straddles an annular groove 38a in the tool block 30, and is supported on a vertical rod 36 secured to the machine knee I, as shown. The downward movement of the forked slide 35a is limited by a shoulder 36a of the rod 36, the latter being adjustable in the knee I0.

In machines, where the machine slide I4 is vertically operated by hand, the upward movement of the tool spindle may also be controlled by check nuts 31 secured to the upper end of the depth rod 36, as will be readily understood.

An important feature of the present invention is the provision oi pressure-actuated means for firmly holding the upper end of the blank when the latter is seated on the work support, andl herein shown as a headless cylindrical blank B recessed in its lower end to substantially t the polygonal arbor end 45 of the work-supporting member on the table El, and countersunk at its upper end, there to be engaged by the lower end of a holding device illustrated as the end portion 4| of a plunger 4l of such diametrical size that ample clearance space is provided between it and the thread-cutting faces of the die head D. The block 38 is bored to constitute a cylinder 42; while the plunger 4I has a flange 43 which constitutes a piston having a sliding iit in the cylindrical bore 42, the plunger 4I acting as a piston rod guided in the tubular interior 28 of the spindle 28, so that, when pressure is applied against the upper end of the rod 4I, the latter will be forced downward until its extreme lower end 4I' is firmly seated within the countersunk recess of the blank, which thus is rigidly held in position on the arbor 40. Inasmuch as this downward movement of the plunger depends upon the downpipe 44 (see Fig. l).

Ward movement of the block 30, for the reason that the piston 43 acts as a limiting stop for the plunger movement. through the block, the end4l will not engage the blank until the block 3U' has been moved downwardly suiciently to nearly bringv the cutting chasers ofthe die D into engagement with the blank, it being understood, however, that the blank is iirxnly held by the plunger, before the chasers actually begin their Work'.r See Figs. 3 and 4.

Reversely, when the. block 3l]y is raised, the threaded blank Bf will not be released until the chasers are clear of the same. See Figs. 5 and 6,

The pressure-producing means consists, in accordance with the present invention, of a body` of oil which is forced into the top of the interior 28; of the tubular spindle 28 through a supply Any suitable mechanism may be employed for connecting the oil supply pipe 44 with the top of the spindle, so as to permit rotation of the latter; while the pipe 44 is not rotatable but may move up and down with the spindle.

Again referring to the plunger 4l above described, there are provided on the outer surface A of the rod one or more longitudinal grooves 45 which permit pressure oil to pass from above the rod into the cylindrical chamber 42 where it becomes effective directly against the piston 43 and therefore exerts a substantially increased downward pressure on the rod or plunger 4|. Furthermore, the piston 43, itself, is also provided with at least one groove 46, permitting oil to pass directly onto the blank below it, so that in this manner the chasers are supplied with the required lubricating medium or cutting oil in an entirely automatic manner, as long as oil is forced into the upper end of the spindle I8.

Variations and modications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim: l. In a screw-threading machine for threading small headless blanks, means for supporting a blank at one of its ends; a die spindle having a threading die thereon movable into threading relation with the blank; and a duid-operated plunger carried by the `spindle and adapted to engage and rigidly hold the blank on the support during the threading operation.

,2. In a screw-threading machine for threading small headless blanks, means for supporting a blank at one of its ends; a die spindle having a threading die thereon movable toward and away from the work-supporting means and into threading relation with the blank; and a uidoperated member carried by the spindle and adapted to engage the free end of the blank before the threading die to rigidly hold the same during the threading operation, said member being relatively movable with respect to the spindle against the pressure of the fluid to permit the threading die to operate on the blank while the same is held in position by said member.

3. In a screw-threading machine, means for supporting the workpiece at one of its ends; a die spindle having a threading die thereon movable toward and away from the work-supporting means and into threading relation with the workpiece; a fluid-operated member carried by the spindle and adapted to engage the workpiece before the threading dies to hold the same during the threading operation, said member being relatively movable with respect to the spindle against the pressure of the fluid to permit the threading die to operate on the workpiece while the same is held in position by said member and also operative to hold the workpiece until after the threading die has been withdrawn from the same; and means for by-passing a portion of said operating fluid around said member to lubricate the workpiece during the threading operation.

4. In a device for externally threading a workpiece, means for supporting the workpiece internally of the same at one of its ends; and a die spindle movable into operative relation with said workpiece and having a relatively movable iiuidoperated member adapted to engage the other end of the workpiece to clamp it to the support during the threading operation, said iiuid-operated member having channels formed therein to divert a portion of the fluid and direct the same to the workpiece whereby the workpiece is lubricated and cooled during the threading operation.

5. In a device for externally threading a workpiece, means for supporting the workpiece internally of the same at one of its ends; and a tubular die spindle movable into operative relation with said workpiece and having a coaxially disposed fluid-operated member mounted for movement therein adapted to engage the other end of the workpiece to clamp it to the support during the threading operation, said member being constructed and arranged to engage the workpiece before the threading operation is initiated.

6.y In a screw-threading machine for cutting threads on small headless blanks, means for supporting a blank at one of its ends; a spindle having threading elements thereon mounted for movement toward and away from the blank; and means carried by the spindle for engaging the other end of the blank and rigidly holding and steadying the same during movement of the threading elements along the blank.

'7. In a screw-threading machine for cutting threads on small headless blanks, means for supporting a blank at one of its ends so that extends upwardly from the support; a spindle movable into operative relation with the blank and having a threading die thereon; a piston operable in a bore in the spindle and having a projecting portion adapted to engage the upper end of the blank and to rigidly hold the same during the threading operation; and means for supplying a fluid under pressure to the bore of the spindle to move the piston and its associated elements into contact with the blank prior to the initiation of the threading operation.

8. In a screw-threading machine, means for supporting a workpiece at one of its ends so that it extends outwardly from the support; a spindle movable into operative relation therewith and having a threading die thereon; a piston operable in a bore in the spindle and having an integral projection thereon adapted to engage the other end of the workpiece, said projection rigidly engaging said workpiece; and means for supplying a fluid to the bore of the spindle to move the projection into contact with the workpiece prior to the initiation of the threading operation, said iiuid also holding the projection in contact with the workpiece during removal of the threading die from the same.

9. In a screw-threading machine, means for supporting a workpiece at one of its ends so that it extends outwardly from the support; a spindle movable into operative relation therewith and having a threading die thereon; a piston operable in a bore in the spindle and having a projection thereon adapted to engage the other end of the workpiece and to rigidly hold the same during the threading operation; and means for supplying a iiuid to the bore of the spindle to move the projection into contact with the workpiece prior to the initiation of the threading operation, the piston moving relative to the spindle against the pressure of the fluid during the threading operation.

10. In a screw-threading machine for cutting threads on small headless blanks, means for supporting a blank at one of its ends; a spindle having a threading die thereon movable into operative relation with said blank; and coaxial means mounted for movement on the spindle and associated with the die for holding the blank to Y the support and also for supplying a lubricant to the blank and die during the threading operation, said means being adapted to engage the blank prior to the initiation of the threading operation and rigidly hold the same to its supporting means.

11. In a, screw-threading machine, means for supporting a workpiece at one of its ends so that it extends outwardly from the support; a spindle movable into operative relation therewith and having a threading die thereon; a piston operable in a bore in the spindle and having a projection thereon adapted to engage the other end of the workpiece; and means for supplying a iluid to the bore of the spindle to move the projection into contact with the workpiece, said piston being provided with passages extending along its length whereby the fluid under pressure may pass through the piston and onto the workpiece to cool and lubricate the same during the threading operation.

12. In a screw-threading machine, an arbor for supporting the workpiece at one of its ends; a driven spindle tube; means for driving said tube; a spindle mounted in said tube for movement therewith; a tool block having a cylinder therein secured to the spindle adjacent said workpiece; a plunger operable in a bore of the tool spindle having a piston formed thereon adapted to slide in the cylinder of said tool block;

a projection carried by said piston; means for moving said spindle and cutter tool into operative relation with said workpiece; and means for supplying a fluid under pressure to the bore of the spindle to move the piston so that the projection contacts and clamps the workpiece prior to the threading operation.

13. In a screw-threading machine, an arbor for supporting the workpiece at one of its ends; a drivenI spindle tube; means for driving said tube; a spindle mounted in said tube for movement therewith; a tool block having a cylinder therein secured to the spindle adjacent said workpiece; a plunger operable in a bore of the tool spindle having a piston formed thereon adapted to slide in the cylinder of said tool block; a projection carried by said piston; means for moving said spindle and cutter tool into operative relation with said workpiece; and means for supplying a fluid under pressure to the bore of the spindle to move the piston so that the projection contacts and clamps the workpiece prior to the threading operation, said piston being provided with passages extending along its length whereby the fluid under pressure may pass through the piston and onto the workpiece to cool and lubricate the same during the threading operation.

14. In a screw-threading machine, an arbor for supporting a workpiece at one of its ends so that it extends upwardly from the support; a tool spindle including'a tool block with a threading die mounted thereon; means for moving said threading die into operative relation with said workpiece; a plunger operable in a bore of the spindle having a piston formed thereon; a cylinder in said tool block coaxially disposed with the bore of said spindle, said piston adapted to be mounted for reciprocal movement in the cylinder of said tool block; a projection carried by said piston; means for supplying a fluid to the bore of the spindle to move the projection into contact with the workpiece prior to the initiation to the threading operation, said uid also holding the projection in contact with the workpiece during the removal of the threading die from the same; and passages formed in the plunger and cylinder to divert a portion of the iluid and direct the same to the workpiece whereby the workpiece is lubricated and cooled during the threading operation.

ERIC J. STAI-ILHAMMER. 

